My cats have first names and nicknames.

Sparkle is Sparkly Warkly, Sparky, and Sweet Stuff! (I almost named her Sweet Stuff, but I couldn't see reprimanding a 4 month old with a straight face if that was her name!)

Vita is Vita Bonita, Vita Baby, Beautiful Lady Cat ( as in dukes and earls, ladies and dames, in royalty)

Chestnut is Sunny Boy, Handsome Fellow, and still Baby Chestnut even though he is now all grown up.

Ruffles is The Duchess or just Duchess. As in the Dowager Duchess in a royal family. Above all the nonsense of the stars of the family, independent and knows it, and the others HAVE to tolerate her, idiosyncracies and all.

Cuddles is Sweet Pea

Crystal is Miss Mischief, Chrissy Cat, and Miss Chris

Ebony doesn't have any yet, we are still trying to get her to recognize her name is Ebony!